TD 17 coming soon--and a scientific first!

By: Dr. Jeff Masters , 9:06 PM GMT on September 16, 2005

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TD 17?
Substantial deep convection has developed in the past few hours in association with well-organized tropical wave about 500 miles east-southeast of the Windward Islands. Spiral banding is more and more conspicuous with each visible satellite image, and if the present trend continues, NHC wil probably initiate advisories on Tropical Depression 17 tonight or tomorrow morning.

The system is in a favorable environment for intensification, now that it has gotten farther from the Equator and can take advantage of the increased spin a higher Coriolis force offers at higher latitudes. Wind shear has decreased to 5 - 10 knots, and the upper-level winds appear favorable--a small upper-level anticyclone is over the wave, and should provide good outflow. Some weak outflow is apparent to the south, and moderately good outflow to the north. Water temperatures are about 29.5C (85F), and increase to about 30C (86F) near the Lesser Antilles Islands.

The early track models are unreliable. The GFDL disippates the system immediately, and the BAMM has been flip-flopping, alternately taking it west-northwest into the Caribbean or northwest, missing the Leeward Islands entirely. The GFS and UKMET models both take the system to the northernmost Leeward Islands, just east of Puerto Rico. The correct solution will depend upon how quickly the system develops, and how quickly a large mid-Atlantic trough north of the islands lifts out. All interests in the Lesser Antilles Islands need to monitor this storm, it has the potential to grow into a hurricane about the time it reaches the islands on Monday.


Figure 1. Early track model runs for the disturbance approaching the Lesser Antilles.

Blob northeast of Puerto Rico
A disturbance northeast of Puerto Rico continues to generate some impressive clusters of thunderstorms, but is not a threat to develop into a tropical depression until Saturday at the earliest. This disturbance is expected to move westward towards the Cuba and the Bahama Islands the next few days. Strong upper level winds out of the west are creating about 10 - 20 knots of shear over the disturbance, down from 20 knots yesterday. The shear should continue to drop the next few days, and may be low enough by Sunday to allow a tropical depression to form. The system could threaten South Florida and Cuba as it continues to track west. Several computer models indicate that the disturbance is more likely to develop once it reaches the Gulf of Mexico, and pose the greatest threat to Mexico. There are no early computer model track points for this disturbance yet, I will post them when they become available.

ITCZ
The Intertropical Convergence Zone (ITCZ), the band of strong thuderstorms between Africa and South America, has historically been the source of many of the severe hurricanes that affect us in September. These "Cape Verde" type storms, so named because they originate from disturbances in the ITCZ near the Cape Verde Islands, have yet to make an appearance during this peak time of hurricane season. The ITCZ has become very active the past few days, and is forecast to continue to remain active the next two weeks. I expect at least one major Cape Verdes type hurricane to form by the end of September. The main activity is across the eastern and central Atlantic is at about 8N latitude, which is probably too far south to generate a tropical cyclone. If some of this activity works its way to 9N, we may have a better chance of development in this area.

Ophelia: a scientific first
A scientific first was accomplished in Ophelia this afternoon--the first ever remotely-piloted aircraft to do a successful penetration of a tropical cyclone flew through Ophelia at 2,500 foot altitude. The drone measured winds of 74 knots. The project is described in detail on the NOAA Hurricane Research Division's web site. The objective is to use the pilotless aircraft in regions where it is too dangerous for humans to fly:

Simply stated, continuous observation of thermodynamic (temperature and moisture) and kinematic (wind) structure of the near-surface hurricane environment has never been documented in a hurricane. This environment, where the atmosphere meets the sea, is critically important since it is where the ocean's warm water energy is directly transferred to the atmosphere just above it. The tropical cyclone surface layer is also important because it is where we find the strongest winds in a hurricane and coincidentally, the level at which most of us live (i.e. at/near the surface). As such, observing and ultimately better understanding this region of the storm is crucial if we hope to improve our ability to make accurate forecasts of TC intensity change. Enhancing this predictive capability would not only save our economy billions of dollars but more importantly it would save countless lives.

Well done, Aerosonde Corporation and NOAA!

Ophelia has intensified a bit this afternoon, with the pressure falling 3 mb. This will be short-lived, however. In fact, the 5pm EDT hurricane hunter eye report found the pressure had risen 2 mb. Ophelia will pass out of the warm Gulf Stream waters and encounter waters as cold as 70F Saturday. She will still generate some trouble on her trek north; expect a 1 - 3 foot storm surge for southeast Massachusetts and Nova Scotia, 1 - 3 inches of rain, and sustained winds up to 40 mph as Ophelia brushes by.

While Ophelia did dump it share of heavy rain--around 5 - 7 inches near Wilmington, and over 10 inches around Cape Fear, south of Wilmington--the rain was mostly confined to the coast, and did not cause widespread flooding problems. Ophelia's winds also did relatively light damage--sustained hurricane force winds (74 mph) were only observed at one location, on Cape Lookout near the Outer Banks. The highest wind gusts measured were 92 mph on Cape Lookout and 83 mph at Cape Hatteras. The storm surge was what caused the main havoc with Ophelia--surges heights of up to 10 - 12 feet were observed along the Neuse River north of Wilmington. Preliminary damage estimates put Ophelia's damage to North Carolina over $10 million, but less than $100 million.


Figure 2. Estimated rainfall from the Morehead City radar for Ophelia's passage.

Jeff Masters

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814. jcpoulard
4:41 PM GMT on September 17, 2005
I don't believe in those model. I'm allmost sure the system will enter the caribean and passs over Haiti as a cat 2 Huricane; make a other lanfall on Cuba go to the west strenth as a cat 3 Hurricane an hit mexico or south of Texas.
Member Since: September 15, 2005 Posts: 4 Comments: 114
813. mybahamas
4:38 PM GMT on September 17, 2005
Eep again :(
812. CFLweather
4:32 PM GMT on September 17, 2005
It will be Phillipe. GFDL for 96l invest looks hard to believe, but remember it is only September 17, and most major hurricanes spawn this time of year. There is no reason why we can't have more cat 4-5 hurricanes by the end of the year. We will soon run out of regular names for storms, so it will be interesting to see how many of the over 20 storms that will end up forming will be major hurricanes. We are 3/7 for major hurricanes compared to total hurricanes.
811. Hawkeyewx
4:20 PM GMT on September 17, 2005
A model run like the latest GFDL certainly makes my eyes pop out with awe, but the GFDL sometimes gets too aggressive too early with systems. It was ultimately pretty right about Katrina in the gulf, but was way too aggressive in forecasting her to bomb out to 930 mb in the northern keys. I also remember the GFDL when TD10 formed(early Katrina when it was where TD17 is now) and the first model runs kept flipping back and forth between dissipating it and bombing it to a cat 3 within four days. We now know the cat 3 scenario northeast of the Leeward islands was bogus and it actually dissipated before eventually reorganizing into Katrina over the Bahamas.

12z GFS is a tad more aggressive with the PR blob, developing it into a storm as it moves through the Florida Straits and then moves it wsw to a spot just off the north Yucatan coast. I think the GFS may be underdeveloping this system as much as the GFDL may be overdoing it. My first gut feeling is with only a few days until this blob reaches Florida it would likely get to cat 1 at best with further strengthening in the southern gulf.
Member Since: July 5, 2005 Posts: 2 Comments: 1924
810. 8888888889gg
4:16 PM GMT on September 17, 2005
when the P storm come will this be girl storm or a boy storm?
809. weatherboyfsu
4:14 PM GMT on September 17, 2005
Hello people....first of all Dr.Masters has a new blog...and second of all, phillipe has joined us......it looks to already have at least 50 or 60 mph winds.....and definitely will be a storm at 5pm...
Member Since: July 17, 2005 Posts: 0 Comments: 1025
808. 8888888889gg
4:12 PM GMT on September 17, 2005
is one she or a boy storm this time around?
807. crow
4:07 PM GMT on September 17, 2005
Relax and check yer shorts . IF and WHEN the BIG gets here, we will adjust to it. This is not WW3
806. WillJax
4:05 PM GMT on September 17, 2005
I am anticipating Dr. Jeff's newest blog entry. He's probably typing it right now and I'm sure he has a lot to say.

007 I was thinking the same thing about that ridge building over the southeast. It could possibly slow the northern movement that is 17's only chance for a fish storm, and deflection to the west is not out of the question.
Member Since: September 7, 2005 Posts: 0 Comments: 33
805. 8888888889gg
4:03 PM GMT on September 17, 2005
wow any one no that we have not 1 not 2 but 3 storm out in the East pacific we got a hurricane Jova with winds of 105 mph we got hurricane kenneth with winds of 120 mph and we got a TD12 with winds of 30mph wow all at one time what up with that?
804. Weatherwatcher007
4:03 PM GMT on September 17, 2005
Gotta go. . . will be back soon.
803. AnonymousBystander
4:03 PM GMT on September 17, 2005
Am I overreacting? Or is this a realistic possibility? Hopefully not... that would be a terrible storm, but judging from the size of the waves now (in consideration to those coming off of the African coast and from which 95l formed into a depression), I can sort of see a correlation.
802. StormJunkie
4:03 PM GMT on September 17, 2005
72 hrs 101mph.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
801. StormJunkie
4:02 PM GMT on September 17, 2005
lol Lefty. Way too early to tell 007. With that initial movement I would think it would be Central FL N for Phillipe if he makes landfall at all. Remeber 7 to 10 days away at best
Member Since: August 17, 2005 Posts: 26 Comments: 16874
800. Weatherwatcher007
4:01 PM GMT on September 17, 2005
I haven't seen the SHIPPS intensity model yet . .. what does it say?
799. leftyy420
4:01 PM GMT on September 17, 2005
ok guys. wanna play with the son some. be bcak later. if u have not done so yet check my blog and pics from my ophelia chase. good stuff. check yall later
Member Since: August 24, 2005 Posts: 35 Comments: 1987
798. StormJunkie
3:59 PM GMT on September 17, 2005
Speed will also play a big factor in any kind of land fall. If the storms should move faster through the slightly cooler waters the more chance of a strong storm making it to landfall.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
797. leftyy420
3:59 PM GMT on September 17, 2005
from florida to delware maybe more north. the whole east coast and if it blows up as big as the canadian suggests, that would be a storm that affects a wide area.
Member Since: August 24, 2005 Posts: 35 Comments: 1987
796. leftyy420
3:58 PM GMT on September 17, 2005
lol 1 by 1 they all see the cnadian model and run in here. sj remebr my reaction last night. this is so funny
Member Since: August 24, 2005 Posts: 35 Comments: 1987
795. Weatherwatcher007
3:57 PM GMT on September 17, 2005
Lefty, StormJ,

How strong do you think the ridge will be IF it builds back in. Were would that bring 17?
794. leftyy420
3:57 PM GMT on September 17, 2005
yeah its the frame site. thats what the f stands for. i like th non frame site better but iwill use what i can get to work. thanks again
Member Since: August 24, 2005 Posts: 35 Comments: 1987
793. AnonymousBystander
3:57 PM GMT on September 17, 2005
http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2005091700&field=Sea+Level+Pressure&hour=Animation

OMG

Look at the SIZE of this thing on the CMC model after 144 hours!
792. StormJunkie
3:56 PM GMT on September 17, 2005
Way to early to speculate 007. We need to see a lot more model runs before we even get an idea of general heading out of the NW movement.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
791. leftyy420
3:56 PM GMT on September 17, 2005
weather while the temops might be down they will have a chance to rebound as this storm is 10+ days away plus right befor landfall is the gulf streem. now i don't see a cat 5 but a cat 3 is not out of the question
Member Since: August 24, 2005 Posts: 35 Comments: 1987
790. CFLweather
3:56 PM GMT on September 17, 2005
It is an alternate site I guess, it's the only one Ive ever had.
789. 8888888889gg
3:55 PM GMT on September 17, 2005
ok right now i am excited fer give me i can not help it
788. Hawkeyewx
3:55 PM GMT on September 17, 2005
Of course the eastern gulf water has recovered some since Katrina and is plenty warm to sustain a good hurricane, but the total heat potential northeast of Katrina's track is not what it was before the storm. The water of the loop current is still plenty capable of supporting a cat 4+, though, and the water from the Bahamas to the Florida straits is pure gas.

It should be noted that at this point only the GFDL, NAM, and Canadian models are forecasting a tropical cyclone to spin up and threaten the keys/south Florida while the other models are just taking an open wave west and wsw across the straits or Cuba and into the western Caribbean and/or the Bay of Campeche. As usual, most models suck until something actually forms and gets a well-defined circulation.
Member Since: July 5, 2005 Posts: 2 Comments: 1924
787. CFLweather
3:55 PM GMT on September 17, 2005
YES, that huge blob is TD17, it is so large though it might be an anomaly. Katrina wasn't even that large with a low pressure field that far from the center.
786. leftyy420
3:53 PM GMT on September 17, 2005
thanks cfl. i think thats a mirror site or something. its a lildifferent than the site i usually use but will do just fine. thanks alot
Member Since: August 24, 2005 Posts: 35 Comments: 1987
785. Weatherwatcher007
3:52 PM GMT on September 17, 2005
Wait a minute?!?! Is that 17 on the cmc model???

If the ridge does build in as 17 moves nw then it may send it west into GA/SC/NC area. I know the sst's left by Ophelia would have an effect.

The blob is becoming a depression soon. If the GFDL is right then FL would be dealing with another catstrophe like it did with Charley. God forbid two major hurricanes striking the Gulf and the southeast one after another. The key is that these are early speculations. The models shift and anything could happen. I hate the early stages of these storms because a SC landfall or a landfall anywhere is the first thing that comes to mind.
784. StormJunkie
3:51 PM GMT on September 17, 2005
888888
Happy and excited/intrested are two different things. Maybe you should look for a better way to describe your emotions.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
783. CFLweather
3:51 PM GMT on September 17, 2005
Link FNMOC is working fine for me.
782. leftyy420
3:50 PM GMT on September 17, 2005
u will see td 18 in 12 -24 hrs
Member Since: August 24, 2005 Posts: 35 Comments: 1987
781. CFLweather
3:50 PM GMT on September 17, 2005
Just thought I would post it, I wasn't aware it had been brought up.

The middle of the storm ends up showing as less than 980 millibars, but how much lower?
780. leftyy420
3:50 PM GMT on September 17, 2005
serveris down. may maitence or soemthing. it sucks i need some microwave data like right now lol
Member Since: August 24, 2005 Posts: 35 Comments: 1987
779. 8888888889gg
3:49 PM GMT on September 17, 2005
ok i will try to stop be so happy but when we start talking about new TD then go to hurrican then that what make me so happy about and i will try to correct my spelling but i am not so good of it so i will try do what i can do for my spelling far give me for being happy on the storm but i can not help it when they make landfall it make me happy so far give me for being up and down so now we have TD 17 will we soon see TD18?
778. StormJunkie
3:49 PM GMT on September 17, 2005
No navy site for me either Lefty, it does not even leave my home page when I click the link. Odd.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
777. leftyy420
3:48 PM GMT on September 17, 2005
thanks wg. have fun with the son
Member Since: August 24, 2005 Posts: 35 Comments: 1987
776. leftyy420
3:48 PM GMT on September 17, 2005
the nhc says it sets the intesity for td 17 to 95 kts in 5 days but its way under the gfdl and ships. they have a problem naming a cat 4 storm in 5 days lol. both the shipd and gfdl blow this thing up. she will be phillipe in 12 hrs or less. looking really impressive
Member Since: August 24, 2005 Posts: 35 Comments: 1987
775. weatherguy03
3:47 PM GMT on September 17, 2005
nope cant get the navy site..tried a few times..must be down..at a time like this..lol..well gotta take my son skateboarding, see ya all later..
Member Since: July 5, 2005 Posts: 592 Comments: 29706
774. StormJunkie
3:47 PM GMT on September 17, 2005
I think we all need to settle down and wait for 79s forcast track.lol.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
773. StormJunkie
3:46 PM GMT on September 17, 2005
That thing is huge CFL. We been talking about that since last night.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
772. leftyy420
3:45 PM GMT on September 17, 2005
yeah thats td 17. i saw that last night. blew my mind
Member Since: August 24, 2005 Posts: 35 Comments: 1987
771. leftyy420
3:44 PM GMT on September 17, 2005
wg lol. hey wg can u acces the navy site
Member Since: August 24, 2005 Posts: 35 Comments: 1987
770. Weatherwatcher007
3:44 PM GMT on September 17, 2005
You are right lefty,

The sst's do make explosive development a possibility. The worst case scenerio would be two cat 4 or 5's threatening the Gulf coast and the southeast coast one after another. I don't know how possible that is though. So many factors. . .
769. CFLweather
3:43 PM GMT on September 17, 2005
Check out the CMC model for sea level pressure for the next 5 days or so, shows a huge storm encompassing the size of the Southeast United States.

Link
768. leftyy420
3:43 PM GMT on September 17, 2005
yeah+ sj i think the bend back will just make her hit se us more than anything.no bend back and she hits near va or nc
Member Since: August 24, 2005 Posts: 35 Comments: 1987
767. weatherguy03
3:42 PM GMT on September 17, 2005
Basically in the short term..TD 17 moves NW...96L moves west...stay tuned..lol..
Member Since: July 5, 2005 Posts: 592 Comments: 29706
766. leftyy420
3:42 PM GMT on September 17, 2005
td 17 will head noeth of just over the islands and its just a matter of the ridge placement but i think a east coast landfall is a likely scenario. i am moreconverned about the pr blob thou.yes andrew blew uo there or maybe a little north of there
Member Since: August 24, 2005 Posts: 35 Comments: 1987
765. weatherguy03
3:41 PM GMT on September 17, 2005
Yeah on both of the systems..the key word again is SLOW..lol..they will not be moving fast, so we will be able to watch both of these..Very difficult ot say with a slow moving system where it is going 7 to 10 days out..
Member Since: July 5, 2005 Posts: 592 Comments: 29706
764. StormJunkie
3:41 PM GMT on September 17, 2005
We are also still in question about how long the NW movement continues for 17. Some of the models hint that a ridge will build over Phillipe and turn him back westward after 4 day or so. Any thoughts on this?
Member Since: August 17, 2005 Posts: 26 Comments: 16874

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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